Internal-combustion motor



Z. JEFFRIES.

INTERNAL COMBUSTION MOTOR.

APPL.ICATION FILED OCT. 23.1916. RENEWED NOV. 8.1919.

1,347,480, Patented July 20, 1920.

UNITED STATES PAiI'ENT OFFICE.

ZAY JEFFRIES, OF EAST CLEVELAND, OHIO, ASSIGNOR TO THE ALUMINUM CASTIN GS COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

INTERNAL-COMBUSTION MOTOR.

Specification of Letters Patent.

Patented July 20, 1920.

Application filed October 23, 1916, Serial No. 127,153. Renewed November 8, 1919. Serial No. 336,734.

bustion Motors, of which the following is a specification,reference being had therein to the accompanying drawing.

inder and piston construction for internal combustion motors.

In order to decrease the weight of such motors, it has recently been proposed to make the cylinder casting and piston of metallic alloys of low specific gravity,'such as alloys of aluminum. In these motors the cylinder casting has been bored out and fitted with a cylindrical liner of iron or steel to take the wear of the piston. While these motors are a notable advance over earlier heavy forms of construction, they have some disadvantages which attach to the liners used. Some advantages accrue from a relatively thin and uniform lining sleeve of ferrous metals, as compared with a unitary cylinder lining of iron; nevertheless, because of the marked difference in the coefficients of thermal expansion of the me tallic alloy'of the piston and the ferrous metal of the liner, it has been necessary to provide a comparatively large clearance between the piston and the liner to avoid seizing when the motor heats up in opera tion.

This large clearance causes piston slap and oil pumping when the motor is starting thermal conductivity of the alloy metals of the piston and of the cylinder casting are materially higher than that of the iron or steel liner, the distribution of the heat in the liner is not as uniform as it otherwise would be and unequal expansion and distortion, and consequently undue friction between the piston and the liner, results. Also by reason of the high thermal conductivity of the alloy metals employed, these motors have tended to run at a temperature too low to secure the highest possible thermodynamic efliciency.

The main object of the present invention is to overcome the foregoing difficulties and this is accomplished by providing a motor with an aluminum alloy piston working in a composite cylinder comprising a. cylinder casting of aluminum alloy bored out to receive a cylindrical liner of specially treated aluminum alloy adapted to withstand the wear of the piston, this liner having a coefficient of thermal expansion .approximately the same as that of the piston and being constructed and arranged in the cy1 TllIS invention relates to an improved cyllnder casting so as to permit .an expansion of the liner corresponding to that of the piston so that the latter can be fitted with a small clearance.

A further object of the invention is the provision of a construction such as last referred to having the cylinder casting and the liner constructed and arranged to permit of the expansion of the liner in relation to the cylinder casting in a manner to control the working temperature of the mo tor.

In order that the invention and the manner of carrying it out may be clearly understood, I will now describe one form of construction embodying the invention.

In the drawing- Figure l is a transverse vertical section of one of the cylinders of an engine embodying my improvements.

Fig. 2 is a side elevation of a cylinder liner.

Fig. 3 is a fragmentary sectional view on an enlarged scale showing the cylinder construction.

Referring in detail to the construction illustrated, l designates the cylinder casting v lar liner 2. IVith the object of producing a cylinder lining member having a coefficient of thermal expansion approximating that of the aluminum alloy piston to be used and having bearing qualities suited to withstand the wear of the piston, I make the liner 2 106 of aluminum alloy of suitable composition for this purpose and form the liner by cast 4 ine the alloy in a permanent metal mold,

and preferably the casting is made by the gravity method. In a liner thus produced 110 the metal is dense and solid throughout and near the surface is characterized by a peculiar density and hardness resulting from the action of the metallic Walls of the mold. Consequently the liner thus produced machines well, it being understood that the softer aluminum alloys are very deficient in this respect, and, in addition, the hard dense texture of the superficial parts of the metal gives the liner excellent wear-resisting qualities.

The liner 2 has its inner surface accurately bored out to receive the .piston. At its upper end the liner is formed with an out-turned flange 2 which fits in a corresponding countersink in the upper end of the cylinder casting, and serves to center the liner in the cylinder bore. At its lower end the liner is similarly centered by an external enlargement or collar 2 which fits the bore of the cylinder casting.

Between the flange 2 and the collar 2* the exterior of the liner is finished with an outside diameter less than the diameter of the bore of the cylinder casting so that when the motor is cold this outer wall of the liner is out of contact with the surrounding wall of the cylinder casting, this clearance being provided to permit the expansion of the liner when the motor warms up. I prefer to make this clearance such that when the parts reach the working temperature, the outer wall of the liner has expanded to bring more or less of its surface into close contact with the surrounding Wall of the cylinder casting.

If desired, the adjacent walls of the cylinder casting and liner may be given plain cylindrical finish so that when the expansion of the liner occurs its surfaceis brought into contact with the surrounding cylinder wall throughout its entire area. I prefer, however, to form the adjacent walls so that only a part of the exterior surface of the liner is brought into close contact 'with the cylinder wall when the expansion occurs, and the transfer'of heat to the water jacket is correspondingly checked and the motor kept at a suitableworking temperature. To this end, in the construction shown, I have depressed or cut away a part of the outer surface of the upper part of the liner lying adjacent the water jacket and have correspondingly depressed or cut away the entire outer surface of that part of the liner extending from the water jacket down to the collar 2. This formation of the outer wall of the liner may readily be accomplished by machining and preferably I form the depression in the upper part of the sleeve by machining a continuous spiral groove 2 thus forming a square spiral thread 2, the outer surface of which comes into contact with the cylinder wall when the liner expands. The amount of clearance" provided der wall,

between the square thread and the sur rounding cylinder wall will depend upon the size of the cylinder and various other factors.

The upper end of the cylinder is closed by a head casting designated as an entirety by 3, this casting having a water jacket 3 communicating in the usual manner with the water jacket 1 of the cylinder casting. The combustion space 4 formed in the head casting has an extension 4 which communicates with the inlet and exhaust passages through valve controlled openings in the usual manner; in the drawing the exhaust valve is shown at 5 and it will be understood that the inlet valve is in that part of the struccrank 8 of the engine shaft 9. This piston is made of aluminum alloy of suitable compo sition. The piston is provided with packing rings 10 of any preferred form and construction, and, in other respects, the piston may be of any suitable form and construc-. tion.

Heretofore in motors with aluminum pistons a relatively large clearance has been provided for the piston, but in my improved motor, since the coefficients of thermal expansion of the piston and cylinder materials are approximately the same, the piston is fitted to the bore of-the liner substantially or nearly as closely. as a cast iron piston would be fitted to the bore of a cast iron cylinder.

In the operation of my improved motor, the cylinder liner when cold is entirely out of contact with the surrounding cylinder wall except at the flange 2" and the collar 2"; but, as the piston and liner absorb heat from the combustion gases, they both expand until the working temperature is reached, at which point, or slightly before it, the outer surfaces of the projecting thread 2 are brought into close contact with the cylin- Until this latter contact is established, the liner is thermally insulated from the surrounding cylinder wall by the inter- .posed envelop of air and consequently the cylinder and piston rise quickly to working temperature and the motor is correspondingly easy to start. As soon as contact between the liner and the surrounding cylinder 7 wall is established, excess heat begins to be conducted to the water jacket and the parts are thus kept at a suitable working temperature.

A composite cylinder, properly designed said other form of construction,

and constructed in accordance with my in vention, has a peculiar automatic governing, action on the working temperature of the engine; for if the temperature falls to a certain value the resultant contraction of the cylinder parts causes the external surface of the liner to draw away from the wall of the cylinder casting so that the conduction of heat to the latter is at once checked and the working temperature of the motor tends to build up again. This action, as stated, is antomatic inits nature.

Furthermore, where aluminum alloys are used as the constituent material of the main cylinder wall or casting as well as of the liner and piston, the relatively high thermal conductivity of all these parts results in a cooling action thatis both effective and 11111 form over the different parts of the cylinder and causes a uniform expansion and cpntraction of the parts, and especially of the liner.

As has been stated, the piston, when the parts are cold, has only the minimum clearance necessary for smooth operation; and, inasmuch asboth piston and cylinder liner expandtogether when the motor heats up, no seizing of the piston occurs but, on the contrary, the small initial clearance is maintained substantially constant. I therefore entirely avoid the objectionable piston slap and oil pumping which has characterized prior motors with iron liners and aluminum pistons.

As I have already indicated, the clearance provided between the outside diameter of the liner and surrounding cylinder wall will depend upon the form and dimensions of the motor and is preferably to be determined in each case experimentally, as is also the area of contact between the liner and cylinder wall. Myexperience indicates that inmost cases the clearance in question will run'between four and ten thousandths of an inch for cylinders running fromthree to four inches in diameter.

In the modified form of my invention, set forth in my copending application Serial, No. 127,152, filed October 23, 1916, the main cylinder wall is formed of iron. I prefer, however, a construction such as is herein set forth both because it results in a reduction in the weight of the engine, in comparison with and also because of the highly effective and uniform cooling, above referred to, which can not be attained with an iron cylinder wall because of its lower thermal conductivity and consequent slower action in conveying heat away from the different parts of the liner.

I have elected to claim in my copending application, above identified, the patentable subject matters common to it and the present application.

Those skilled in the art will understand that various changes in the form and prothe said liner portions of the parts may be made in carrying out my invention. The construction herein set forth i for purposes of illustration and explanation and in no sense intended as a limitation of my invention.

What I claim is:

1. In an internal combustion motor, the combination with a composite cylinder comprising an aluminum alloy casting with a cylindrical wall surrounded by cooling means, and a cylindrical liner secured concentrically within the said cylindrical wall, the said liner being made of a metallic alloy having a high coefiicient of thermal expansion approximating that of the alloy of the said casting and having its outside diameter less than the diameter of the inner wall of the casting .to afford a clearance between the liner and casting adapted to be taken up by the expansion of the liner when heated by the internal combustion within the motor,

of an aluminum alloy piston arranged to reciprocate in the liner.

2. In an internal combustion motor, th

combination with a composite cylinder comprising an aluminum alloy casting with a cylindrical wall surrounded by cooling means, and a cylindrical liner secured concentrically within the said cylindrical wall, being made of a metallic alloy having a high coefficient of thermal expansion approximating that of the alloy of the said casting and having its outside diameter less than the diameter of the inner wall of the casting to afford a clearance between the liner and casting adapted to be taken up by the expansion of "the liner when heated by the internal combustion within the motor, and part of one of the adjacent surfaces of the cylinder wall and liner being recessed to form heat insulating space between said adjacent surfaces, of an aluminum alloy piston arranged to reciprocate in the liner. 3. In an internal combustion motor, the combination with a composite cylinder comprising an aluminum alloy casting with a cylindrical wall surrounded by cooling means, and a metal mold cast cylindrical liner of aluminum alloy secured concentrically within the aforesaid cylindrical wall, the liner having its outside diameter less than the diameter of the adjacent inner wall of the casting to afford a clearance between the liner and casting adapted to be taken up by the expansion of the liner when heated by the internal combustion within the motor, of an aluminum alloy piston arranged to reciprocate in the liner.

4. In an internal combustion motor, the combination with a composite cylinder comprising a casting with a cylindrical wall surrounded by cooling means, and a cylindrical liner secured concentrically within the said wall of the casting to afford a clearance between theliner and casting adapted to be taken up by the expansion of the liner when heated by the internal combustion within the the liner having its outside diameter less motor, of a piston arranged to reciprocate in the liner, the said casting, liner and piston being made of metals having approximately the same coeflicients of thermal expansion.

5. In an internal combustion motor, the combination with a composite cylinder comprising a light weight metallic alloy casting with a .cylindrical wall surrounded by cooling means, and a cylindrical liner secured concentrically within said cylindrical Wall,

than the diameter of the inner wall of the casting to afl'ord a clearance between the liner and casting adapted to be taken up by the expansion of the liner when heated bythe internal combustion within the motor, of a light Weight metallic alloy piston ar ranged to reciprocate in the liner, the said liner being made of metal having a coeffiliner and casting adapted to be taken up by the expansion of the liner when heated by the internal combustion within the motor, and part of one of the adjacent surfaces of the cylinder wall and liner being recessed to form heat insulating space between said adjacent surfaces, of a light weight metallic alloy piston arranged to reciprocate in the liner, the said liner being made of metal having a coeflicient of thermal expansion approximately the same as those of the cylinder casting and piston metals.

7. In an internal combustion motor, the combination with a composite cylinder comprising a main cylindrical wall formed of metal having, in comparison with iron, a low specific gravity and a high coeflicient of thermal conductivity, cooling means on the outer side of said cylindrical wall, and a metallic liner secured concentrically within the said cylindrical wall and having its outside diameter less than the inner diameter of the cylindrical wall to afford a clearance adapted to be taken up by the expansion of tlie liner when heated by the internal combustion within the motor, of a piston arranged to reciprocate in the liner and formed of metal having a low specific gravity in comparison with iron, the said liner having a coefiicient of expansion approximately the same as that of the piston and a high 00- efficient of thermal conductivity in comparison with iron. I

In testimony whereof I hereunto aflix my signature.

' ZAY J EFFRIES. 

